reconstruction with megaprothesis after bone and joint ressection. prof. rodolfo capanna

MEGASYSTEM C

Department of Oncological and Reconstructive Surgery CTO Florence Italy

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Eclectic Device Different Clinical Conditions

posttraumaticrevisiontumor

MEGASYSTEM C



ModularityFrom a minimum of 5 cm

(revision surgery)

to the“en bloc” knee

&entire femur and tibia

(extensive tumor resection)

MEGASYSTEM C



Modularity

Accurate length adjustment 1cm by 1cm( instead 2 by 2 )

1 cm

2cm

MEGASYSTEM C



Further accomodationwith extension ring

in hip reconstructionsPDF created with pdfFactory Pro trial version www.pdffactory.com


Complete Hip Joint System

- hip arthroplasty

conventionalsnap fitfully retentive

- bypolar cup

- saddle prosthesis

MEGASYSTEM C



üAntiversion - adjustable at surgery

MEGASYSTEM C



Newendomodel

kinematic rotating hinge knee

MEGASYSTEM C



Intraoperative changeable from rotational to total hinged knee without removing stems or joint components

Component for rotation and extension/flexion

Component forextension/flexion only

Assembly without extension between femur and tibia

MEGASYSTEM C



MEGASYSTEM C



Same system :3 Extensive revisions3 Resection arthroplasty3 Intercalary resections3 Resection arthrodesis

Conversionfrom arthroplasty

to arthrodesisfeasible at any time

without stem removal

MEGASYSTEM C



Stem fixation

Interchange ability

cemented cementless

Older pt. Younger pt.Metastases Primary tumorsOsteoporotic Normal bonePrevious Rxth. NoneScheduled Rxth. NoneInadequate press fitt Adequate press fit

MEGASYSTEM C



Rough Collar Ring

Cemented stem

MEGASYSTEM C



enhanced scar tissueprevents

polyethilene debrismigration

at the interfacestem / inner cortex

“purse string effect”

MEGASYSTEM C



Cementless fixation

Rough titanium trunco conical flanged stems (1 mm steps)

MEGASYSTEM C



Cementless fixation

Two antirotational pegs

MEGAPROSTHESIS C



The anchorage elements absorbs rotational forces acting on the intramedulary stem anchorage. This

assures a bone-safe transmission between the anchorage of the prosthesis and the bone

MEGASYSTEM C



short coneconnection

MEGASYSTEM C



Conventional megaprosthesis

Composite allograft- prosthesis

Ibrid solutions“encased grafts”

Implant Flexibility

MEGASYSTEM C



MEGASYSTEM C






Implant Flexibility

MEGASYSTEM C



üThe allograft allows a

normal distribution of

forces from implant to

host bone when union

has been achieved

Rationale for alloprosthesis



Alloprostheses vs Megaprostheses:Outcome (10 years survival)

Alloprosthesis Megaprosthesis

Anract 77 noneZehr 76 58Capanna 85 83Robb -- 63Horowitz -- 67Urwin -- 94



Alloprostheses vs Megaprostheses:Functional Results

Alloprosthesis Megaprosthesis

score limp can score limp can

Zehr 87 64 43 80 90 60

Anract 83 52 10 75 75 35






Implant Flexibility

MEGASYSTEM C



Rationale for alloprosthesisReattachment of bone and muscles is feasable and effective



osteosarcoma

MEGASYSTEM C



allograft

conventional



MEGASYSTEM C : “conventional” tibia



MEGASYSTEM C : tibial “ encased graft ”



Chondrosarcoma involving the entire tibia with pathological fracture & closed nail fixation



Osteoarticularwith

capsular repair



5 years follow up



Recurrent G. C. T.

extensivelyinvolving

the knee joint

MEGASYSTEM C : knee “ ibrid” implant



SERIES OF PATIENTSTotal 297 cases

Department of Orthopaedics, Florence, Italyfrom june 2001 to july 2007

213 casesUniversity of Innsbruck, Austria

from maj 2002 to july 200760 cases

University of Hamburg, Germany24 cases



SERIES OF PATIENTS297 cases

RECONSTRUCTION TYPE CASES

Proximal femur 130 (44%)

Distal femur 108 (36%)

Total femur 35 (12%)

Proximal tibia (sept. 2005) 10 (3.2%)

A-P composite of the knee 8 (3%)

Knee arthrodesis 5 (1.5%)

Intercalary resection of the femur 1 (0.3%)



COMPLICATIONS297 cases

34 cases (11.4%)Type Florence Innsbruck Hamburg Tot.

Infection 14 1 2 17 (5.7%)Mechanical failure

6 1 - 7 (2.3%)

Dislocation 3 - 1 4 (1.3%)Loosening 2 1 - 3 (1%)Shaft perforation - 2 - 2 (0.6%)Prosthetic disconnection

1 - - 1 (0.3%)



PROSTHETIC COMPLICATIONS

17 out of 297 cases ( 6 %)

Type Florence Innsbruck Hamburg Tot.

Cone breakage 6 1 - 7 (2.3%)Hip dislocation 3 - 1 4 (1.3%)Stem loosening 2 1 - 3 (1%)Shaft perforation - 2 - 2 (0.6%)Cone disconnection

1 - - 1 (0.3%)



Mechanical failureFlorence experience

Total # %213 pts 6 2.8%493 cones 8 1.6%



Further recent improvements

Modification on cone

slope obliquityshiftingstress

distributionmore at its basis



Mechanical failurePersonal experience

Total # %Before 150 pts 5 3.3

322 cones 7 2.1

Total # %After 63 pts 1 1.5

171 cones 1 0.6PDF created with pdfFactory Pro trial version www.pdffactory.com



Transfixing screws for cone stability

were foundprudentialexcessive

tools

Elimination of any stress riser or week pointPDF created with pdfFactory Pro trial version www.pdffactory.com



• Full thicknesscone

with total contact• Removal of

transfixing screws

To avoid any stress riser or week pointPDF created with pdfFactory Pro trial version www.pdffactory.com


Further recent improvements :biomechanical tests

Disassembling forces :

6500 N without screw8000 N with screw

Very safe locking device



Further recent improvements :biomechanical tests

Small screw grippingin a notch of the

collar

very effectivelocking device(up to 8000 N )in a safe area



Further recent improvements :biomechanical tests3 points bending stresses :

3500 N 10 Hz 10,000,000 cycles

No failure PDF created with pdfFactory Pro trial version www.pdffactory.com


ALLOGRAFT COMPLICATIONS

TYPE NUMBER EFFECT

PARTIAL RESORPTION &

FRACTURE

1 CASE(PROX FEM)

NO INFLUENCE ON FUNCTIONAL OUTCOME

PARTIAL RESORPTION

1 CASEREMOVAL AFTER 4 YEARS REVISION FOR COTYLOIDITIS

POST-TRAUMATIC EXTENSOR APPARATUS ELONGATION

1 CASE EXTENSOR LAG



PRE RESORPTION & FRACTURE



POST RESORPTION&

FRACTURE



ALLOGRAFT COMPLICATIONS

TYPE NUMBER EFFECT

PARTIAL RESORPTION & FRACTURE

1 CASE(PROX FEM)

NO INFLUENCE ON FUNCTIONAL OUTCOME

PARTIAL RESORPTION 1 CASE

REMOVAL AFTER 4 YEARS REVISION FOR COTYLOIDITIS

POST-TRAUMATIC EXTENSOR APPARATUS ELONGATION

1 CASE EXTENSOR LAG



reconstruction with megaprothesis after bone and joint ressection. prof. rodolfo capanna

Documents

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